You will find this picture inside almost every home, shop and temple in Bhutan. It illustrates the story of Thuenpa puen shi, or the Four Cooperative Friends. The story tells how four very different creatures, an elephant, a monkey, a rabbit and a peacock, combined to find food. The peacock found the seed, the rabbit watered it, the monkey fertilised it, and the elephant guarded it. The problem was that the tree grew too high for any one of them to pick the fruit. So, they stood on each other's backs in order to reach it (obviously, the elephant was not on top). The Bhutanese are officially the happiest people in the world. Maybe this story helps to explain why.
Whilst you will find the Four Cooperative Friends inside, on the outside walls of their shops and houses the Bhutanese have painted a very different picture: it is of a giant penis with a ribbon tied round it. Whether this also has something to do with them being so happy, I really don't know.